How To Clean Yamaha Cr 420 Volume Control

Hi folks,
I'm totally new to this forum and just joined for some help I will surely need for restoring my old Yamaha CR-420 which I merely picked up at a waste separation site. I managed to download a user manual and all it's schematics from hither:

http://www.eserviceinfo.com/downloadsm/ ... R-420.html

and

http://safemanuals.com/user-guide-instr ... AHA/CR-420

Although I didn't find it's service manual. Today I connected it to the mains since it had it's power cable cutting, but only partially worked. The signal meter and some lights didn't work and when I attached an antenna and tuned, the FM stereo LED never turned on. I'm really looking forward to see information technology up and running. I accept quite a bones knowledge in electronics, do you experts retrieve it is possible to fix it? Do you know of whatever checklist that I can follow to test the components after each other? (ex. starting with the most prone to blowing out)

Johnnysan

If the stereo light does not come up i, either it is not receiving a stereo indicate, or the lamp is bad or there is a problem in the multiplex excursion.
Have you lot listened to the receiver to determine if it is switching from mono to stereo?

gary rabbitt · **Posted:** April Mon 05, 2010 8:20 am

So, information technology did receive stations? From both speakers?

Perhaps in that location is a Stereo/Mono switch?

You are in Malta (?) is there a nearby stereo station you lot used to exam?

If you listen with headphones, yous may be able to hear seperation in the channels.

The light may be burned out, or the lite driver might not exist functioning.
Stereo reception all the same may be taking place.

trojsi · **Posted:** Apr Mon 05, 2010 11:00 am

Hi,
I didn't receive any stations... neither any hiss! Simply I found something interesting. When I switch on the unit of measurement and test with a multi meter... there are to wires that connect the ability supply circuit to the radio excursion: i) +12V 2) +30V . The + 30v is not giving me annihilation on the voltmeter and the +12v is giving me 13v which i recall information technology'southward normal. At least now I know where I need to tackle. Can you please guide me from the shematic which component from the Power supply circuit shall I check beginning?

1 more thing ... when I check the p.d. beyond the +30v and +12v it is giving me +13v... is that considering the 30v bacame gnd because of the error ?

thanks

Brandon

Johnnysan

Could exist a bad transistor or shorted capacitor in the power supply, or a bad connexion; await for poor solder connections first.

HadYourPhil · **Posted:** Apr Mon 05, 2010 1:21 pm

_________________
Nosotros improve things by making them worse...

trojsi

I followed the +30V trace and it was connected to a 2SC1175 NPN transistor... and I removed it. Anyone knows a simple procedure to test it because I am not trusting my multi meter hFE. I desire to exam with the diode method. If information technology's blown should I replace it with the exact one if I don't find the verbal match?

Tube Radio · **Posted:** Apr Mon 05, 2010 3:57 pm

You need this transistor if yours is bad:
ON Semiconductor MPS8099G

trojsi

Another problem unfortunately - I dismantled the tuning signal meter and information technology was jammed - sprayed some WD-40 and it loosened well but the jump mechanis is not working and when given some electric current information technology will deflect but doesn't return to it's neutral position. Do you know of anywhere I can find them online please?

tuning meter :

http://i145.photobucket.com/albums/r223 ... R-420a.jpg

brandon [/img]

Johnnysan

You probably don't need an verbal friction match for that transistor; an NPN of similar case style that is rated at around 80 volts and upwards to 1 amp should work fine.
Y'all might want to expect for any open resistors in that power supply circuit.
Do yous have a good source for electronic parts where y'all live?

trojsi · **Posted:** April Mon 05, 2010 9:30 pm

bdw ... it's a moving coil galvanometer that has both a negative and positive scale ... here is a video of a restored Yamaha on youtube

http://world wide web.youtube.com/lookout man?v=7Oo7zsFPWGs

y'all can see how information technology works and what type is it. I need ane like that.. it doesn't have to be with the encompass I only demand the moving curlicue mechanism and than fit it in the cover with the scale backside.

trojsi · **Posted:** Apr Tue 06, 2010 10:11 pm

I replaced that transistor with a BC 639 .. as the human being at the shop found that they can be used instead of MSP.. When soldered information technology to the pcb and switched on, another transistor when bang and there where fuems coming out of information technology(because I forgot to reattach the large sink). Amazingly when I removed it form the PCB it looked stilll intact and when tried with it once more 2 cement molded resistor where glowing yellowish and I switched off the plug immediatly. When I tried to switch on once again to make sure what was glowing fuems where coming out of the spark quenching capacitor that is continued to the main switch of the unit of measurement then I switched of over again. Is that possible for a 2SB595 transistor to remain functional after fuems had been coming out of it considering I checked it with a multi meter and it is giving me an hfe of 32 ?

Johnnysan · **Posted:** Apr Midweek 07, 2010 2:23 am

If any transistor is smoking information technology can't be trusted to work properly once more; it has to exist replaced. The 2SB595 is a PNP transistor. Those 2 resistors will need to be replaced too.
The next step is to check if there is a brusk on the 30 volt line.

trojsi · **Posted:** Apr Wednesday 07, 2010 12:10 pm

some good news mates... I fastened the GND steel back beyond the 2 circuits with screws, switched the unit of measurement on and I'm hearing some proficient reception from the rec tape output when I fastened it to some other amplifier. At present the next step is to fix the amplifier by replacing the transistor and resistors that yesterday were deliberating some scary smoke. Do you thing a unit of measurement from the early on 1970'south needs some replacement of electrolytic capacitors?

Brandon

johnS. · **Posted:** Apr Thu 08, 2010 7:01 am

"Practise y'all matter a unit from the early on 1970's needs some replacement of electrolytic capacitors?"

Do you have a capacitor checker? If not, start by replacing the ability supply caps, and if you are notwithstanding having weak reception in the tuner, or distorted audio from the amp (or pre-amp), you may encounter bad caps in those sections. That's why it's handy to have a cap checker. This is just similar repairing a small transistor radio, but on a larger scale. As caps age, most will become leaky (lose their capacitance). You may be lucky and not have to change annihilation, but I would but go ahead and replace the filter caps in the power supply, and go from there. If the Yamaha is indeed from the early on 70'south, those caps are now about 40 years former! Replacing the power supply electrolytics volition requite you "pease of mind", and may just make any slight hum go away, as well. Merely my stance.

I own a Yamaha receiver from the mid 1990's, which I bought new at Sears. I don't come across replacing it with anything else in the most hereafter. It's a prissy sounding piece of equipment. Every one time in a while, I open up the cover and accident out the dust to help keep it running libation.

John S.

trojsi · **Posted:** Apr Thu 08, 2010 11:06 am

Is it because that I removed a transistor that is in accuse of 1 aqueduct that there is no output from the two channels?

trojsi

Another problem emerged

the fm stereo LED is not lighting up. It is connected to a Ziener diode which is connected to 470ohm resistor and to a LA-350 3A IC. What practice y'all call back is the about likely fault?

FM Refugee · **Posted:** Apr Friday 09, 2010 4:46 pm

...Do y'all take FM reception, merely not in stereo? First, do y'all have the muting switch on? If you have the muting switch turned off, that too disables your FM stereo. If the muting is on and you're non getting stereo reception, your FM stereo decoder is not working.
...That LA3350-3A is your FM stereo (MPX) decoder IC. It is a PLL blazon decoder, with VR101 setting its VCO frequency. If that is out of adjustment the IC won't be able to decode FM stereo signals and you won't get your FM stereo LED and all your FM stations will be in mono. You could effort tuning in a station that yous know should be in stereo and carefully and slowly adjust VR101, and see if at some bespeak the LED comes on (and you hear a distinct departure in the sound as it is at present in stereo)...
...If you know you have stereo reception with the LED not working, see if that resistor (R135) or the zener diode (D105) is open up, or if C149 (1µF 50V) is shorted; besides endeavour pressing on pin six of the IC (in instance of a bad solder joint), and check that the brownish wire going from the main circuit board to the LEDs isn't broken somewhere...

gmcjetpilot · **Joined:** Jul Wed 22, 2009 8:32 am **Posts:** 3668

trojsi wrote:

Some other problem unfortunately - I dismantled the tuning point meter and it was jammed - sprayed some WD-40 and it loosened well just the spring mechanis is non working and when given some electric current it volition deflect but doesn't return to it'southward neutral position. Do you know of anywhere I can find them online please?
tuning meter:

http://i145.photobucket.com/albums/r223 ... R-420a.jpg

brandon

These meters are likewise chosen: permanent-magnet moving-coil meter or more than accurately d'Arsonval movement.

If you need a new meter you would be best trying to find a good used part.... On eBay right at present is an auction for a Yamah CR-620 middle tune meter. LINK

I would never shoot WD40 into meter movement. Just shooting liquid and propellant at high velocity into that sensitive movement could damage it. WD40 may get out residue and not be compatible with the materials. If you harm or upset the coil jump or "pilus bound" information technology can be impossible to get back. Spraying WD40 into the meter tin can cause it to un-gyre and tangle. If a meter is working, never take information technology apart. I learned this lesson the hard way. They are very sensitive, hard to work on and piece of cake to damage.

Meters stick for several reasons. Some times information technology is the spring, but usually it is other issues. If a meter is subject to daze or abuse it can impairment the pivot. I dubiety the center tune meter was subject area to much abuse. Some other common cause of a sticking meter is clay or a bit of metal coming off the magnet. This gets between the moving ringlet & magnet, causing it to stick. Getting the garbage or flakes out can be done successfully sometimes with a magnifying glass, stiff light and tiny tools, strips of tape. Y'all fish out the trash. Again yous have to exist conscientious not to damage the spring.

To find a "generic" replacement meter y'all need to know the specification of the meter move. You demand to know the sensitivity, volts to fully deflect meter. The value is in volts, uV or mV. Some times it is given in amps, mA or uA. Measure the resistance of the whorl. The meter must have the same resistance. Y'all need to know this first. The YouTube video shows a eye reading meter, where zero is center, so it can indicate positive and negative voltage.

I think finding a generic replacement meter movement that fits in the original housing will be difficult. You may become lucky, only commencement find the sensitivity. Your best bet is eBay or other Howdy-Fi sites and say you desire to purchase a meter for your stereo. Some one may have a replacement.

Expert luck/

Author	Bulletin
	Postal service subject: Yamaha CR-420 reviving attempt :) Posted: Apr Sun 04, 2010 x:31 pm
New Member Joined: April Lord's day 04, 2010 4:54 pm Posts: 15 Location: Santa Lucija	Hi folks, I'm totally new to this forum and just joined for some help I will surely need for restoring my old Yamaha CR-420 which I merely picked up at a waste separation site. I managed to download a user manual and all it's schematics from hither: http://www.eserviceinfo.com/downloadsm/ ... R-420.html and http://safemanuals.com/user-guide-instr ... AHA/CR-420 Although I didn't find it's service manual. Today I connected it to the mains since it had it's power cable cutting, but only partially worked. The signal meter and some lights didn't work and when I attached an antenna and tuned, the FM stereo LED never turned on. I'm really looking forward to see information technology up and running. I accept quite a bones knowledge in electronics, do you experts retrieve it is possible to fix it? Do you know of whatever checklist that I can follow to test the components after each other? (ex. starting with the most prone to blowing out)
Pinnacle

Johnnysan	Post subject: Posted: April Sun 04, 2010 ten:43 pm
Joined: Jan Thu 01, 1970 1:00 am Posts: 16795 Location: Albuquerque, NM 87123	If the stereo light does not come up i, either it is not receiving a stereo indicate, or the lamp is bad or there is a problem in the multiplex excursion. Have you lot listened to the receiver to determine if it is switching from mono to stereo?
Height

trojsi	Post discipline: Posted: Apr Mon 05, 2010 11:00 am
Joined: Apr Sun 04, 2010 iv:54 pm Posts: fifteen Location: Santa Lucija	Hi, I didn't receive any stations... neither any hiss! Simply I found something interesting. When I switch on the unit of measurement and test with a multi meter... there are to wires that connect the ability supply circuit to the radio excursion: i) +12V 2) +30V . The + 30v is not giving me annihilation on the voltmeter and the +12v is giving me 13v which i recall information technology'southward normal. At least now I know where I need to tackle. Can you please guide me from the shematic which component from the Power supply circuit shall I check beginning? 1 more thing ... when I check the p.d. beyond the +30v and +12v it is giving me +13v... is that considering the 30v bacame gnd because of the error ? thanks Brandon
Top

Johnnysan	Post subject: Posted: Apr Monday 05, 2010 eleven:10 am
Joined: Jan Thu 01, 1970 1:00 am Posts: 16795 Location: Albuquerque, NM 87123	Could exist a bad transistor or shorted capacitor in the power supply, or a bad connexion; await for poor solder connections first.
Top

trojsi	Post subject: Posted: Apr Monday 05, 2010 two:l pm
Joined: April Sun 04, 2010 iv:54 pm Posts: 15 Location: Santa Lucija	I followed the +30V trace and it was connected to a 2SC1175 NPN transistor... and I removed it. Anyone knows a simple procedure to test it because I am not trusting my multi meter hFE. I desire to exam with the diode method. If information technology's blown should I replace it with the exact one if I don't find the verbal match?
Meridian

How To Clean Yamaha Cr 420 Volume Control

Yamaha CR-420 reviving try :)

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trojsi	Postal service bailiwick: Posted: Apr Mon 05, 2010 viii:46 pm
Joined: Apr Lord's day 04, 2010 4:54 pm Posts: 15 Location: Santa Lucija	Another problem unfortunately - I dismantled the tuning signal meter and information technology was jammed - sprayed some WD-40 and it loosened well but the jump mechanis is not working and when given some electric current information technology will deflect but doesn't return to it's neutral position. Do you know of anywhere I can find them online please? tuning meter : http://i145.photobucket.com/albums/r223 ... R-420a.jpg brandon [/img]
Summit

Johnnysan	Post subject: Posted: Apr Mon 05, 2010 ix:06 pm
Joined: Jan Thu 01, 1970 1:00 am Posts: 16795 Location: Albuquerque, NM 87123	You probably don't need an verbal friction match for that transistor; an NPN of similar case style that is rated at around 80 volts and upwards to 1 amp should work fine. Y'all might want to expect for any open resistors in that power supply circuit. Do yous have a good source for electronic parts where y'all live?
Height

trojsi	Post subject: Posted: April Mon 05, 2010 9:30 pm
Joined: Apr Sun 04, 2010 iv:54 pm Posts: 15 Location: Santa Lucija	bdw ... it's a moving coil galvanometer that has both a negative and positive scale ... here is a video of a restored Yamaha on youtube http://world wide web.youtube.com/lookout man?v=7Oo7zsFPWGs y'all can see how information technology works and what type is it. I need ane like that.. it doesn't have to be with the encompass I only demand the moving curlicue mechanism and than fit it in the cover with the scale backside.
Height

trojsi	Mail subject: Posted: Apr Tue 06, 2010 10:11 pm
Joined: Apr Sun 04, 2010 4:54 pm Posts: 15 Location: Santa Lucija	I replaced that transistor with a BC 639 .. as the human being at the shop found that they can be used instead of MSP.. When soldered information technology to the pcb and switched on, another transistor when bang and there where fuems coming out of information technology(because I forgot to reattach the large sink). Amazingly when I removed it form the PCB it looked stilll intact and when tried with it once more 2 cement molded resistor where glowing yellowish and I switched off the plug immediatly. When I tried to switch on once again to make sure what was glowing fuems where coming out of the spark quenching capacitor that is continued to the main switch of the unit of measurement then I switched of over again. Is that possible for a 2SB595 transistor to remain functional after fuems had been coming out of it considering I checked it with a multi meter and it is giving me an hfe of 32 ?
Top

Johnnysan	Post subject field: Posted: Apr Midweek 07, 2010 2:23 am
Joined: Jan Thu 01, 1970 1:00 am Posts: 16795 Location: Albuquerque, NM 87123	If any transistor is smoking information technology can't be trusted to work properly once more; it has to exist replaced. The 2SB595 is a PNP transistor. Those 2 resistors will need to be replaced too. The next step is to check if there is a brusk on the 30 volt line.
Height

trojsi	Post discipline: Posted: Apr Wednesday 07, 2010 12:10 pm
Joined: Apr Sun 04, 2010 iv:54 pm Posts: 15 Location: Santa Lucija	some good news mates... I fastened the GND steel back beyond the 2 circuits with screws, switched the unit of measurement on and I'm hearing some proficient reception from the rec tape output when I fastened it to some other amplifier. At present the next step is to fix the amplifier by replacing the transistor and resistors that yesterday were deliberating some scary smoke. Do you thing a unit of measurement from the early on 1970'south needs some replacement of electrolytic capacitors? Brandon
Top

trojsi	Post subject: Posted: April Thu 08, 2010 2:ten pm
Joined: Apr Sun 04, 2010 4:54 pm Posts: 15 Location: Santa Lucija	Another problem emerged the fm stereo LED is not lighting up. It is connected to a Ziener diode which is connected to 470ohm resistor and to a LA-350 3A IC. What practice y'all call back is the about likely fault?
Top

gmcjetpilot	Post subject: Posted: Apr Sat 10, 2010 4:35 am
Joined: Jul Wed 22, 2009 8:32 am Posts: 3668	trojsi wrote: Some other problem unfortunately - I dismantled the tuning point meter and it was jammed - sprayed some WD-40 and it loosened well just the spring mechanis is non working and when given some electric current it volition deflect but doesn't return to it'southward neutral position. Do you know of anywhere I can find them online please? tuning meter: http://i145.photobucket.com/albums/r223 ... R-420a.jpg brandon These meters are likewise chosen: permanent-magnet moving-coil meter or more than accurately d'Arsonval movement. If you need a new meter you would be best trying to find a good used part.... On eBay right at present is an auction for a Yamah CR-620 middle tune meter. LINK I would never shoot WD40 into meter movement. Just shooting liquid and propellant at high velocity into that sensitive movement could damage it. WD40 may get out residue and not be compatible with the materials. If you harm or upset the coil jump or "pilus bound" information technology can be impossible to get back. Spraying WD40 into the meter tin can cause it to un-gyre and tangle. If a meter is working, never take information technology apart. I learned this lesson the hard way. They are very sensitive, hard to work on and piece of cake to damage. Meters stick for several reasons. Some times information technology is the spring, but usually it is other issues. If a meter is subject to daze or abuse it can impairment the pivot. I dubiety the center tune meter was subject area to much abuse. Some other common cause of a sticking meter is clay or a bit of metal coming off the magnet. This gets between the moving ringlet & magnet, causing it to stick. Getting the garbage or flakes out can be done successfully sometimes with a magnifying glass, stiff light and tiny tools, strips of tape. Y'all fish out the trash. Again yous have to exist conscientious not to damage the spring. To find a "generic" replacement meter y'all need to know the specification of the meter move. You demand to know the sensitivity, volts to fully deflect meter. The value is in volts, uV or mV. Some times it is given in amps, mA or uA. Measure the resistance of the whorl. The meter must have the same resistance. Y'all need to know this first. The YouTube video shows a eye reading meter, where zero is center, so it can indicate positive and negative voltage. I think finding a generic replacement meter movement that fits in the original housing will be difficult. You may become lucky, only commencement find the sensitivity. Your best bet is eBay or other Howdy-Fi sites and say you desire to purchase a meter for your stereo. Some one may have a replacement. Expert luck/ _________________ Tube: AM/FM Zeniths, RCA, TrueTone table tops; Transistor: Kaito KA1103, TenTec RX320D, Pioneer SX780
Top